THE MODULATION OF OXIDATIVE STRESS WITHIN THE EARLY BOVINE EMBRYO AND ITS EFFECTS ON DEVELOPMENT
Bibliographic record
Abstract
Oxidative stress induced by reactive oxygen species (ROS) is believed to influence embryo loss during in vitro production systems. To better understand the impact of oxidative stress on embryo development, the ROS concentration of the in vitro culture environment was modulated through either the treatment of hydrogen peroxide (H2O2) or the addition of the antioxidant enzyme Catalase to the embryo culture. Groups (r=3) of embryos (n=100) were treated with a concentration series (0, 50, 150 and 250 μM) of hydrogen peroxide (H2O2). Additionally, a single dosage of H2O2 (250 μM) was applied to groups (r=3) of embryos (n=100) at various stages of pre-attachment development. Lastly, groups (r=3) of embryos (n=100) were treated with a concentration gradient (0, 1, 10 and 20 U/embryo) of PEG-conjugated catalase. In all experimental groups developmental progress was assessed on the 9th day of culture, with assessments of viability and apoptosis being made with calcein and TUNEL staining respectively. The treatment of 2–4 cell embryos with increasing doses of H2O2 produced a significant (P<0.05) decrease in the proportion of embryos that developed into blastocysts as well as a significant (P<0.05) increase in the proportion of embryos arrested at the 2–4 cell stage. The treatment of immature oocytes, zygotes and 9–16 cell embryos with 250 μM ofH2O2 resulted in the cessation of cleavage division in addition to the onset of apoptosis. Interestingly, the treatment of 2–4 cell embryos with 250 μM of H2O2 ceased cleavage division but failed to induce apoptosis. Furthermore, embryos treated at the 2–4 cell stage continued to exhibit positive staining for cell viability. The treatment of zygotes with increasing concentrations of PEG-catalase resulted in a significant (P<0.05) decrease in the proportion of 2–4 cell arrested embryos with 1U/embryo of PEG-catalase producing a significant (P<0.05) increase in the proportion of embryos that developed into blastocysts. It was concluded that 1) excessive ROS can induce either embryo arrest or apoptosis, 2) the mode of embryo loss induced by ROS is dependent upon the developmental stage at which the stress occurs, 3) while beneficial at lower doses, excessive antioxidants can interfere with successful development. These results indicate that the early bovine embryo appears to be sensitive to intracellular ROS levels that outside of an optimal range, will result in various pathways of embryo loss. (poster)
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".